Peroxide Definition and Facts

A peroxide is defined as a polyatomic anion with molecular formula O₂^2-. The compounds are generally classed as ionic or covalent or an organic or inorganic. The O-O group is termed the peroxo group or peroxide group.

Peroxide also refers to any compound containing the peroxide anion.

• Hydrogen peroxide, H₂O₂, is a simple peroxide compound.
• Other inorganic peroxides (aside from hydrogen peroxide) are known. These are classified as either ionic peroxides or covalent peroxides. Ionic peroxides contain alkali metal ions or alkaline earth ions as their cations. Covalent peroxides include hydrogen peroxide and also peroxymonosulfuric acid (H₂SO₅).
• Technically superoxides, ozones, ozonides, and dioxygenyls are peroxide compounds, but they tend to be considered separate because of their special characteristics.

• Peroxides occur naturally in small amounts in plants and animals, water, and the atmosphere. In humans and other animals, hydrogen peroxide is a by-product of biochemical reactions. The chemical is short-lived but is toxic to cells because of its ability to oxidize DNA, proteins, and membrane lipids. This toxicity makes peroxide useful as a disinfectant, to kill bacteria and other pathogens. However, nearly all eukaryotic cells purposely form peroxide in organelles called peroxisomes. Peroxisomes are used for catabolism of fatty acids, D-amino acids, and polyamines and for biosynthesis of compounds essential for normal lung and brain function.
• The enzyme catalase uses peroxide to oxidize substrates to neutralize toxins in the kidney and liver cells. In this way, for example, humans are able to metabolize ethanol into acetaldehyde.
• Plants use hydrogen peroxide as a signaling chemical indicating defense against pathogens.
• Some peroxides can bleach or decolorize organic molecules, so they are added to cleaning agents and hair colorants.
• Peroxides are widely used to synthesize drugs and other chemicals.
• The bombardier beetle stores hydroquinone and hydrogen peroxide in abdominal reservoirs. When the beetle is threatened, it mixes the chemicals together, resulting in an exothermic reaction that enables the beetle to squirt boiling-hot, smelly liquid at a threat.

Most people are familiar with household hydrogen peroxide solution, which is a dilute solution of hydrogen peroxide in water. The type of peroxide sold for disinfecting and cleaning is about 3% peroxide in water. When used to bleach hair, this concentration is called V10. Higher concentrations may be used to bleach hair or for industrial cleaning. While 3% household peroxide is a safe chemical, concentrated peroxide is extremely dangerous!

Peroxides are potent oxidizers, capable of causing serious chemical burns.

Certain organic peroxides, such as TATP (triacetone triperoxide) and HMTD (Hexamethylene triperoxide diamine), are highly explosive. It's important to understand these highly unstable compounds may be made by accident by mixing together acetone or other ketone solvents with hydrogen peroxide. For this, and other reasons, it's unwise to mix peroxides with other chemicals unless you have full knowledge of the resulting reaction.

Peroxidic compounds should be stored in opaque containers, in cool, vibration-free locations. Heat and light accelerate chemical reactions with peroxides and should be avoided.